Hi Piotr,
First of all where are you in Poland? Had two visits there as my father was Polish, and have another trip planned for 2017. As far as engine upgrades are concerned the Mountune 375 is Ford backed and doesn’t invalidate the warranty. Or that’s what I am led to believe, I would hold off any upgrades in power for the moment until we know if there are any issues with the car in standard tune. A power upgrade could be done say on first service when the car is bedded in. There are members on here who have already upgraded power output and many more planning to.
Coastliner